| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 | 
                                                                 
                                    
                                    18.4%
                                 
                                                             | 
                                                        
                    
| 0 | None | 25 | 
                                                                 
                                    
                                    65.8%
                                 
                                                             | 
                                                        
                    
| 2 | 3 | 
                                                                 
                                    
                                    7.9%
                                 
                                                             | 
                                                        
                    |
| 5 | 3 | 
                                                                 
                                    
                                    7.9%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 337 |